Conventionally, there have been widely known techniques to adjust the positional relationship between a projector and a screen or between or among lenses so as to change the size and shape of a display area projected onto the screen.
Such techniques are disclosed in, e.g., the following literature:
Patent Literature 1: Unexamined Japanese Patent Application KOKAI Publication No. H9-54374.
Due to restrictions on the positional relationship between a projector and a screen and the orientations thereof, the shape of a display area projected onto the screen eventually becomes trapezoidal. Patent Literature 1 proposes a technique to correct trapezoidal distortions on a liquid crystal projector using a prism.
Adjustment of the size of a display screen or correction of the shape thereof is in general performed by a user who is actually looking at the display screen.
Adjustment of the size of a display screen or correction of trapezoidal distortions can be seen as one form of coordinate conversion, and calculation therefor can be performed by computer. For example, one perspective and projection technique for three-dimensional (3D) graphics defines, as the display position of the object, the position where the line connecting the viewpoint and an object in a virtual 3D space intersects the projection plane. By determining the positional relationship between the projection plane and the viewpoint and which region of the projection plane should be actually displayed, adjustment of the size of a display screen and simulation for trapezoidal distortion corrections can be performed.
The display screen of a game, etc. usually displays graphical images (i.e., images illustrating a virtual world by presenting the background, characters, etc.) and graphical images (i.e., images showing the text of character speeches, explanations of the game, etc.) which are often superimposed in the form of a window display. The player plays the game by looking at graphical and text-containing images displayed on the television or computer display device that the player is using.
When using traditional game devices, in order to adjust the sizes of graphical and text-containing images to be displayed on the display screen, the player in general adjusted the size of the display screen by properly constructing settings of the aspect ratio (e.g., 4:3 or 16:9) and the display resolution of the display screen.